1. Field of the Invention
The present invention generally relates to a mobile communication terminal and, more particularly, to an apparatus and method for improving qualities of motion and still images to be output in a mobile communication terminal.
2. Description of the Related Art
Mobile phones on the market today are mobile communication terminals in which multimedia functions, such as two-to-eight mega pixel digital camera functions and the like, as well as broadcast service functions for Digital Video Broadcasting-Handheld (DVB-H), Digital Multimedia Broadcasting (DMB), etc., are embedded to process high-quality images. Up-to-date mobile communication terminals may process high-quality media data in a 24-bit color representation scheme by adopting a superior system processor and memory than those of legacy systems.
Although internal structures of systems for processes and memories of mobile communication terminals continuously develop, display devices of mobile communication terminals, that is, Liquid Crystal Displays (LCDs), do not follow the development speed of the internal structures of the systems. Today, a majority of up-to-date mobile communication terminals use LCD display devices limited to 65,536 color representations in a 16-bit color representation scheme. Thus, high-quality images stored in a system in which 16,777,216 color representations are possible in a 24-bit color representation scheme are quantized to 16-bit colors once more in an LCD display device. A user can view only an image of 16-bit color quality due to a physical limitation of display hardware even when an original image is of 24-bit color quality.
In general, when a 24-bit color image has a Red-Green-Blue (RGB) color format, 8 bits are allocated to color signals of red, green, and blue. In a 16-bit color image different from a 24-bit color image, 5 bits are allocated to red, 6 bits are allocated to green, and 5 bits are allocated to blue. The three colors are mixed to generate a color image. When a 24-bit color image is converted into a 16-bit color image, errors occur upon quantization since bits allocated to red are reduced by 3 bits, bits allocated to green are reduced by 2 bits, and bits allocated to blue are reduced by 3 bits. For this reason, image quality is degraded. There is a problem in that discontinuous color variation occurs due to a difference from the original image.
To solve quantization errors, a color printer or Plasma Display Panel Television (PDP TV) uses an error diffusion process. A known error diffusion process diffuses quantization errors between an original pixel and a quantized pixel to four neighboring pixels around the quantized pixel. When the four neighboring pixels to which the quantization errors are diffused are fed back, visual quantization errors can be reduced.
Research has been conducted to more efficiently reduce quantization errors than those of the feedback mechanism of four neighboring pixels. Research results show that quantization errors can be efficiently reduced by reflecting random weights in current quantization errors. FIG. 1 shows a conventional example of weights provided in an error diffusion process to reduce quantization errors.
In FIG. 1, N3 100, N4 106, N5 104, and N6 102 are neighboring pixels around a current quantized pixel. In an error diffusion process, different random values are allocated based on positions of the neighboring pixels. The different random values are 7/16, 1/16, 5/16, and 3/16, as shown in FIG. 1.
In FIG. 1, 7/16 of the quantization error of the current quantized pixel is diffused to N3100, 3/16 of the quantization error of the current quantized pixel is diffused to N4 106, 5/16 of the quantization error of the current quantized pixel is diffused to N5 104, and 1/16 of the quantization error of the current quantized pixel is diffused to N6 102. When the above-described error diffusion process is completed, N3 100 is quantized. In this case, 5/16of the quantization error occurred in a process for quantizing N3 100 is diffused to N6 102 and 3/16 of the quantization error occurred in the process for quantizing N3 100 is diffused to N5 104.
Whenever one pixel is quantized, some pixels around the current quantized pixel partially receive the quantization errors of the current quantized pixel. Quantization errors are continuously accumulated. Since the quantization errors occurring in the error diffusion process are diffused to neighboring pixels, an error due to a quantization error between the neighboring pixels can be reduced.
This error diffusion process has a problem in that a computation amount increases since computations in a range of real numbers, such as 7/16, 5/16, 3/16, and 1/16, are necessary for neighboring pixels whenever one pixel is quantized, as shown in FIG. 1. In a relatively large printer or PDP TV, an additional processor is provided to process operations in the error diffusion process in order to achieve a fast response rate. An internal system is designed in which operations can be parallel processed in an error diffusion process. At a fast response rate, image quality improved by error diffusion can be provided to users.
However, a size of a mobile communication terminal is limited due to mobility and portability. It is difficult to provide an additional process in the limited size. When a parallel processing scheme of an additional processor is not used, there is a problem in that a response rate may be significantly reduced according to a computation amount in the error diffusion process. For these reasons, an error diffusion method may not be applied to current mobile communication terminals.